Powertrain, generic (extended)

P21E3 Cylinder 4 Injector B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P21E3 marks a high circuit state on the cylinder 4 B injector, normally a short to a supply line. On Mitsubishi's 2022 Eclipse Cross, where B is the direct high-pressure injector, the fault must persist 2 s; it closes the manual's list of direct injector circuit codes for the four cylinders. Because the direct injector driver uses boosted voltage, Mitsubishi tells technicians not to probe the terminals with a voltmeter and to work with resistance and continuity checks instead. GM's 2019 LT5 V8 assigns the same code to the supplemental injector of cylinder 4, stored as Type A when the low side sits within 0.5 Ohm of power with the driver off. The low counterpart is P21E2, the port injector high code on Mitsubishi P0271; from P21E4 on, the series continues with cylinder 5.

Likely causes

Cylinder 4 injector line shorted to a supply wire
Injector of cylinder 4 shorted internally
Driver stage in the ECM or injection module damaged

Symptoms

  • Check engine light on
  • Misfire on cylinder 4 (P0304)
  • Engine runs with reduced torque if further cylinders are affected

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–900
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injectorinjector wiringengine control module

Related codes

P21E2P21D2P0271P21E1P21E5P0304

References: mitsubishitechinfo.com, gsi.ext.gm.com.